You dont have to craete the Administrator account , it is alreay present but is hidden all you have to do is enable it....check the link posted earlier for the same it tells the step you need to follow.

Go to Administrator account.

Open Illustrator check , does it work fine , If yes....go to User/Administrator/Appdata/Roaming/Adobe/Adobe IllustratorCS5 Settings, copy it and paste it in your users folder

I think it is because my settings folder is empty. I've reinstalled the program several times and the settings folder for cs5 is empty. That can't be normal. ive done everything suggested so far in this thread

If you are not even getting the splash screen then that folder will be empty , because it is the preferences folder and preferences get created when the program luanches but in your case this not happening.

Secondly , all the troubleshooting done earlier except Uninstall and re-install ,is product specific however however I dont think that is the case in your situation.

Go to C:\Users\<username>\AppData\Local\Temp

locate amt3.log , delete it

Launch your Illustrator , it will crash

then go back to C:\Users\<username>\AppData\Local\Temp

and collect the amt3.log and paste it on Pastebin.com website and provide the link here , to analysis